Spin-transfer torque induced domain wall ferromagnetic resonance in nanostrips

Wang, Xi-guang; Guo, Guang-hua; Zhang, Guangfu; Nie, Yao-zhuang; Xia, Qinglin; Li, Zhixiong

doi:10.1016/j.jmmm.2012.12.013

Cited by 16 publications

(10 citation statements)

References 34 publications

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“…Actually, the mode here can be recognized as the DW thickness oscillation mode (or breathing mode), i.e., the DW thickness oscillates around the equilibrium value D 0 , meanwhile, the magnetization tilts out of the wall plane (x-z plane) with an oscillation angle u, which is antisymmetrical with respect to the wall center. [27][28][29] The little difference between the DW resonant frequency (7.2 GHz) for u ¼ 0 m/s and the frequency (7 GHz) at which the maximum velocity occurs for u ¼ 50 m/s is originated from the redshift of the DW thickness resonant frequency induced by STT. Similar spin-wave frequency shift induced by STT has been reported in various systems, such as bulk ferromagnetic metal, nanostrips with and without DWs.…”

Section: Resultsmentioning

confidence: 98%

Current-driven domain wall motion enhanced by the microwave field

Wang

Guo

Nie

et al. 2014

Journal of Applied Physics

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The magnetic domain wall (DW) motion driven by a spin-polarized current opens a new concept for memory and logic devices. However, the critical current density required to overcome the intrinsic and/or extrinsic pinning of DW remains too large for practical applications. Here, we show, by using micromagnetic simulations and analytical approaches, that the application of a microwave field offers an effective solution to this problem. When a transverse microwave field is applied, the adiabatic spin-transfer torque (STT) alone can sustain a steady-state DW motion without the sign of Walker breakdown, meaning that the intrinsic pinning disappears. The extrinsic pinning can also be effectively reduced. Moreover, the DW velocity is increased greatly for the microwave-assisted DW motion. This provides a new way to manipulate the DW motion at low current densities.

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Section: Resultsmentioning

confidence: 98%

Current-driven domain wall motion enhanced by the microwave field

Wang

Guo

Nie

et al. 2014

Journal of Applied Physics

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“…A slight decrease in the PM frequency with width is observed in simulation, which is the expected trend based on increases in the DW width and out-of-plane anisotropy. We have also observed modes internal to the DW in simulation that are characterized by a spatially non-uniform amplitude and phase [22], but due to their nonuniformity we expect a weak coupling to the optical probe.…”

mentioning

confidence: 67%

Resonance in magnetostatically coupled transverse domain walls

et al. 2014

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We have observed the eigenmodes of coupled transverse domain walls in a pair of ferromagnetic nanowires. Although the pair is coupled magnetostatically, its spectrum is determined by a combination of pinning by edge roughness and dipolar coupling of the two walls. Because the corresponding energy scales are comparable, the coupling can be observed only at the smallest wire separations. A model of the coupled wall dynamics reproduces the experiment quantitatively, allowing for comparisons with the estimated pinning and domain wall coupling energies. The results have significant implications for the dynamics of devices based on coupled domain walls.

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“…Idealizing the TDW as a string crossing the nanostrip, this mode has similarities to a standing wave with a zero-displacement node (dm ≈ 0) near y = 0. Wang et al 32 have observed what seem to be similar breathing and twisting modes of unpinned TDWs. As shown below, and in contrast to what is observed for the translational mode, a finite frequency for the breathing and twisting modes is non-reliant on confinement (i.e.…”

Section: Tdw Modesmentioning

confidence: 82%

“…These methods require the system to be subjected to an external excitation 11,32,[39][40][41] , often a pulsed magnetic field. In contrast, eigenmode methods 42,43 enable a direct calculation of resonant magnetic modes from a system's equilibrium magnetic configuration, m 0 (r) (as do dynamical matrix methods 44 ).…”

Section: Micromagnetic Simulation Methodsmentioning

confidence: 99%

“…The TDWs are pinned at triangular notches located at the edge of the strip. We use a numerical eigenmode method to study three TDW resonances, corresponding to translational 8,9,14,31 , twisting 11,32 and breathing 8,[33][34][35][36][37] excitations of the TDW. The latter mode has recently been studied for oscillator applications 38 and we demonstrate that this mode has the lowest sensitivity to changes in notch depths, making it an appealing choice for device applications.…”

Section: Introductionmentioning

confidence: 99%

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Resonant translational, breathing, and twisting modes of transverse magnetic domain walls pinned at notches

et al. 2016

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We study translational, breathing and twisting resonant modes of transverse magnetic domain walls pinned at notches in ferromagnetic nanostrips. We demonstrate that a mode's sensitivity to notches depends strongly on the characteristics of that particular resonance. For example, the frequencies of modes involving lateral motion of the wall are the ones which are most sensitive to changes in the notch intrusion depth (especially at the narrower, more strongly confined end of the domain wall). In contrast, the breathing mode, whose dynamics are concentrated away from the notches is relatively insensitive to changes in the notches' sizes. We also demonstrate a sharp drop in the translational mode's frequency towards zero when approaching depinning which is found, using a harmonic oscillator model, to be consistent with a reduction in the local slope of the notch-induced confining potential at its edge.

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Spin-transfer torque induced domain wall ferromagnetic resonance in nanostrips

Cited by 16 publications

References 34 publications

Current-driven domain wall motion enhanced by the microwave field

Current-driven domain wall motion enhanced by the microwave field

Resonance in magnetostatically coupled transverse domain walls

Resonant translational, breathing, and twisting modes of transverse magnetic domain walls pinned at notches

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